I am mostly stuck on question 8b, please help me on this.
8 Dan has a mass of 62 kg. He is travelling at a speed of 11 m s–1 at the top of a
rollercoaster loop, which is 21.8 m above the ground.
a Calculate:
i his kinetic energy at the top of the loop (1 mark)
ii his change in gravitational potential energy between the top and bottom
of the loop 0.8 m above the ground (2 marks)
iii his kinetic energy at the bottom of the loop, stating any assumption you
have made in calculating your answer (3 marks)
iv his speed at the bottom of the loop. (2 marks)
b Dan started the ride 5 m above the ground.
i Calculate the minimum work done by the accelerating force to accelerate
him to the top of the loop in part a. (2 marks)
ii Explain why the work done will be more than this minimum